OpenSCAD User Manual/WIP/Module Literals

module literals / module references A module_reference is a type of variable that refers to a module Module literal and module reference syntax The module_reference is initialised using a module_literal. In the following snippet my_cube is the module_reference and module cube([2,3,4]) is the module_literal. A module literal is an expression which is syntactically identified by being prefixed with the module keyword. Syntax in detail There are several ways to define a module reference, depending on what you want to do. Simple syntax In this syntax you define the module exactly as you want to see it output. // Create a reference to a cube module my_cube = module cube([2,3,4]); The above code creates the variable my_cube but doesn't instantiate it, so there will be no output in the graphics window. To instantiate the module you use the existing syntax that you use with modules. // Instantiate the module through the module reference my_cube();thumb|Instantiated module reference Alias syntax In this variation, the name of the module reference is just another name for the module. my_cylinder = module cylinder; To instantiate the module, the alias takes exactly the same arguments as the module it aliases my_cylinder(h=20, r=10, center=true);thumb| Instantiated module reference Arguments forwarding syntax In another form you provide arguments to the module_literal. The arguments are forwarded to the original module. my_cylinder = module(height) cylinder(h = height, r=10, center=true); In this case you call the reference with the modified arguments my_cylinder(20);thumb| Instantiated module reference Anonymous module syntax without arguments In the final forms you can create an anonymous module_literal and initialise the reference to it. ( Note that in this form there must be a semicolon after the closing curly brace ) my_shapes = module { cube(2,center = true); translate([5,0,0]) sphere(1,center = true); }; The module can be instantiated in the usual way. my_shapes();thumb|Instantiated module reference Anonymous module syntax with arguments The anonymous module form can of course also take arguments my_rotated_square = module ( r, s) { rotate(r) square(s);}; The module reference is instantiated in the usual way. my_rotated_square(45,10);thumb|Instantiated module reference Instantiating a module via an expression Module literals can be stored in arrays and returned from functions In these cases it can be inconvenient to assign them to a symbol before invoking them. You can instantiate an expression resolving to a module_literal by encasing the expression before the instantiation arguments, in parentheses. //------------- // n is an integer index between 0 and 3 // choose_shape returns the shape given by the index function choose_shape(n) = let (ar = [ module cube([5,20,30]), module sphere(r = 6 , $fn = 20), module cylinder(d = 15, h = 20, $fn = 30) ]) ar[n]; //-------------- // instantiate the chosen module (choose_shape(2))(); // choose the cylinder Further examples For more advanced uses of module_literals and module references see https://github.com/kwikius/openscad/tree/module_literal_v3/examples/ModuleLiterals